Layered heater system with honeycomb core structure

ABSTRACT

A layered heater system is provided, which includes an engineered substrate, a heater substrate disposed on the engineered substrate, a resistive element layer formed proximate the heater plate, and a protective layer formed on the resistive element layer. Terminal pads are formed over at least a portion of the resistive element layer and are exposed through the protective layer. The engineered substrate includes a plurality of walls which extend in a thickness direction of the engineered substrate and which have a thickness engineered for specific heat transfer requirement.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 12/405,722, filed Mar. 17, 2009, which claimspriority to U.S. Provisional Patent Application Ser. No. 61/037,549,entitled “Layered Heater System With Honeycomb Core Structure,” filedMar. 18, 2008, the contents of which are incorporated herein byreference in their entirety and continued preservation of which isrequested.

FIELD

The present disclosure relates generally to resistive heaters and moreparticularly to layered heaters for use in relatively large flat panels.

BACKGROUND

The statements in this section merely provide background informationrelated to the present disclosure and may not constitute prior art.

Resistive devices such as layered heaters are typically used inapplications where space is limited, when heat output needs vary acrossa surface, or in ultra-clean or aggressive chemical applications. Alayered resistive device, such as a layered heater, generally compriseslayers of different materials, namely, a dielectric and a resistivematerial, which are applied to a substrate. The dielectric material isapplied first to the substrate and provides electrical isolation betweenthe substrate and the resistive material and also minimizes currentleakage during operation. The resistive material is applied to thedielectric material in a predetermined pattern and provides a resistiveheater circuit. The layered heater also includes leads that connect theresistive heater circuit to a heater controller and an over-moldmaterial that protects the lead-to-resistive circuit interface.Accordingly, layered load devices are highly customizable for a varietyof applications.

Individual layers of the resistive devices can be formed by a variety ofprocesses, one of which is a “thick film” layering process. The layersfor thick film resistive devices are typically formed using processessuch as screen printing, decal application, or film printing heads,among others. Some thick film layered heaters are employed in relativelylarge flat panels, such as those used in preheat cabinets for a plasmaenhanced chemical vapor deposition (PECVD) process. In these cabinets,several heater shelves are employed, which heat substrates for the PECVDprocess, and are relatively large in size and thus are relatively heavy.As such, the heater substrates often deflect, or sag, under their ownweight, which affects thermal performance of the overall system.Additionally, the heater substrates may exhibit a certain degree ofwarpage after a thick film manufacturing process if coefficients ofthermal expansion of the layered heater materials and the substrate arenot properly matched, or due to other manufacturing variations. Anadditional issue related to such heater substrates is that of creep,especially at elevated temperatures.

Additionally, these heater substrates in the art do not allow for heattransfer control from one shelf of heater substrates to the next. Sincethe opposing faces of heater substrates are not thermally isolated fromeach other, heat is transferred from one heater substrate to the next,which can be both beneficial and detrimental, depending on the desiredoperating characteristics. Moreover, isolation of electrical connectionsto the heater in a vacuum environment to prevent accidental discharge ofelectricity is often challenging in such applications.

SUMMARY

In one form of the present disclosure, a layered heater system isprovided, which includes an engineered substrate, a heater substratedisposed on the engineered substrate, a resistive element layer formedproximate the heater plate, and a protective layer formed on theresistive element layer. Terminal pads are formed over at least aportion of the resistive element layer and are exposed through theprotective layer. The engineered substrate includes a plurality of wallswhich extend in a thickness direction of the engineered substrate andwhich have a thickness engineered for specific heat transferrequirement.

In another form, a layered heater system is provided that includes anengineered substrate including an upper face sheet, a lower face sheet,and a core disposed between the upper face sheet and the lower facesheet. A dielectric layer is formed proximate at least one of the upperface sheet and the lower face sheet, a resistive element layer is formedon the dielectric layer, and a protective layer is formed on theresistive element layer. Terminal pads are formed over at least aportion of the resistive element layer, wherein the terminal pads areexposed through the protective layer.

Various electrical interconnects for use in connecting terminal pads ofthe layered heater system to a power supply in a vacuum environment arealso provided. Such an environment may also include the introduction ofplasma into the vacuum environment, for which the present disclosure isalso intended for use.

Further areas of applicability of the present disclosure will becomeapparent from the detailed description provided hereinafter. It shouldbe understood that the detailed description and specific examples, whileindicating the embodiments of the disclosure, are intended for purposesof illustration only and are not intended to limit the scope of thedisclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description and the accompanying drawings, wherein:

FIG. 1 is a perspective view of a layered heater system constructed inaccordance with the principles of the present disclosure;

FIG. 2 is a partial cross-sectional view, taken along line A-A of FIG.1, illustrating the layered heater system with an engineered substrateconstructed in accordance with the principles of the present disclosure;

FIG. 3 is a cross-sectional view of one form of a layered heater systemwith an engineered substrate that defines a honeycomb core structureconstructed in accordance with the principles of the present disclosure;

FIG. 4 is a partial top view of the layered heater system having ahoneycomb core structure in accordance with the principles of thepresent disclosure;

FIG. 5 is a cross-sectional view of the layered heater system having atemperature sensor and constructed in accordance with the principles ofthe present disclosure;

FIG. 6a is a cross-sectional view of another form of the layered heatersystem having a heater plate and constructed in accordance with theprinciples of the present disclosure;

FIG. 6b is a cross-sectional view of yet another form of the layeredheater system having a heater plate and constructed in accordance withthe principles of the present disclosure;

FIG. 6c is a cross-sectional view of still another form of the layeredheater system having a heater plate and constructed in accordance withthe principles of the present disclosure;

FIG. 7 is a cross-sectional view of another form of the layered heatersystem having a core defining a frame structure constructed inaccordance with the principles of the present disclosure;

FIG. 8 is an exploded view of an electrical interconnect assembly foruse in connecting terminal pads of a resistive heater to a power supplyin a vacuum environment and constructed in accordance with theprinciples of the present disclosure;

FIG. 9 is a perspective view of an electrical interconnect in accordancewith the principles of the present disclosure;

FIG. 10 is a cross-sectional view of the electrical interconnect inaccordance with the principles of the present disclosure;

FIG. 11 is a cross-sectional view of another form of an electricalinterconnect constructed in accordance with the principles of thepresent disclosure;

FIG. 12 is an exploded top view of yet another form of an electricalinterconnect constructed in accordance with the principles of thepresent disclosure;

FIG. 13 is an exploded bottom view of the electrical interconnect ofFIG. 12 in accordance with the principles of the present disclosure;

FIG. 14 is a cross-sectional view taken through a housing of theelectrical interconnect of FIGS. 12 and 13 in accordance with theprinciples of the present disclosure;

FIG. 15 is a cross-sectional view taken through another form of anelectrical interconnect wherein the electrical interconnect is on oneside of a substrate and the layered heater is on the other side of thesubstrate and constructed in accordance with the principles of thepresent disclosure;

FIG. 16 is a perspective view of another form of an electricalinterconnect constructed in accordance with the principles of thepresent disclosure;

FIG. 17 is an exploded view of the electrical interconnect in accordancewith the principles of the present disclosure; and

FIG. 18 is a cross-sectional view of the electrical interconnect inaccordance with the principles of the present disclosure.

Corresponding reference numerals indicate corresponding parts throughoutthe several views of the drawings, and the drawings are not to scale.

DETAILED DESCRIPTION

The following description of the embodiments is merely exemplary innature and is in no way intended to limit the disclosure, itsapplication, or uses.

Referring to FIGS. 1-2, a layered heater system is illustrated andgenerally indicated by reference numeral 20. The layered heater system20 comprises an engineered substrate 22 having an upper face sheet 24, alower face sheet 26, and a core 28 disposed between the upper face sheet24 and the lower face sheet 26. In one form, a dielectric layer 30 isformed on the upper face sheet 24 as shown, although it should beunderstood that a dielectric layer 30 could be formed on either or bothof the upper face sheet 24 and the lower face sheet 26. A resistiveelement layer 32 (shown dashed in FIG. 1) is formed on the dielectriclayer 30, and a protective layer 34 is formed on the resistive elementlayer 32. As further shown, terminal pads 36 (shown dashed in FIG. 1)are formed over at least a portion of the resistive element layer 32,wherein the terminal pads 36 are exposed to an outside environment, orto other components, through the protective layer 34. Each of thelayers, in one form, are formed by a thick film layering process,although it should be understood that other thick film processes such asthin film, thermal spraying, or sol-gel, or a combination thereof, maybe employed while remaining within the scope of the present disclosure.Such processes are set forth in greater detail in copending applicationSer. No. 10/752,359, titled “Combined Material Layering Technologies,”which is commonly assigned with the present application and the contentsof which are incorporated herein by reference in their entirety.

If the engineered substrate 22 is a nonconductive material, the layeredheater system 20 can be employed without the dielectric layer 30,wherein the resistive element layer 32 would be formed directly on, orproximate, the engineered substrate 22, with the protective layer 34formed on the resistive element layer 32 as set forth above. Such alayered heater system without a dielectric layer 30 shall be construedas falling within the scope of the present disclosure.

Referring to FIGS. 3 and 4, in one form, the core 28 defines a honeycombcore structure 40. The honeycomb core structure 40 comprises a pluralityof cells 42 that have walls 44 as shown. Each of the walls defines athickness, which can be engineered for specific heat transferrequirements. For example, thicker walls 44 will result in increasedheat transfer between the upper face sheet 24 and the lower face sheet26, which may be required in certain applications. On the other hand,thinner walls 44 will result in increased thermal isolation between theupper face sheet 24 and the lower face sheet 26, which may be requiredin other applications. Moreover, and with specific reference to FIG. 4,the cells define a peripheral size, which is essentially the overallsize of each cell, which is shown as 0.125 inches (0.049 cm) in one formof the present disclosure. It should be understood that this size ismerely exemplary and that other sizes may be employed depending on theload requirements of the application. As such, the peripheral size canbe tailored for specific load carrying capability.

In one form, the face sheets 24 and 26 are a stainless steel materialsuch as 430 or 304, however, it should be understood that othermaterials may be employed while remaining within the scope of thepresent disclosure. For example, Nickel super alloys such Inconel® maybe used, and/or Titanium for both the face sheets 24, 26, and the walls44. Advantageously, stainless steel will resist creep at temperatures inexcess of those that aluminum, for example. As such, the disclosureprovides a light-weight structure that relatively stiff and that alsoresists creep. It should be understood that a variety of materials forthe face sheets 24, 26 and the walls 44 may be employed while remainingwithin the scope of the present disclosure. For example, an austeniticstainless steel material for the walls 44 may be used with a ferriticmaterial for the face sheets 24 and 26.

Referring now to FIG. 5, the layered heater system 20 in one formincludes a temperature sensor 50. The temperature sensor 50 in this formis disposed within a thermowell 52, which extends through the core 28 asshown. A plurality of apertures 54 are formed through the individualwalls 44 of the cells 42 in order to accommodate the thermowell 52,which in one form, is brazed to the core 28 as shown. It should also beunderstood that any number of thermowells 52 and temperature sensors 50may be provided while remaining within the scope of the presentdisclosure.

With the honeycomb core structure 40, or the engineered substrate 22,the layered heater system 20 exhibits much higher stiffness-to-weightratios that traditional flat panel designs. As such, the layered heatersystem 20 in accordance with the principles of the present disclosureresists deflection or sagging, and also resists thermal warpage toprovide a superior heater solution.

Another form of the layered heater system 20 is illustrated in FIG. 6a ,wherein a heater plate 60 is disposed proximate the engineered substrate22, and then the layers as set forth above are disposed on the heaterplate 60 rather than directly onto the engineered substrate 22. Morespecifically, the dielectric layer 30 is formed on the heater plate 60,the resistive element layer 32 formed on the dielectric layer 30, andthe protective layer 34 is formed on the resistive element layer 32. Asfurther shown, the terminal pads 36 are formed over at least a portionof the resistive element layer 32, wherein the terminal pads 36 areexposed to an outside environment, or to other components, through theprotective layer 34. Similar to the previous form of the presentdisclosure, the heater plate 60 may be provided on either one or both ofthe face sheets 24 and 26 of the engineered substrate 22. Additionally,if the heater plate 60 is nonconductive, the dielectric layer 30 can beeliminated as set forth above, where the resistive element layer 32 isdisposed directly onto the heater plate 60.

As shown in FIG. 6b , the present disclosure in this form includes theability to decouple and/or tailor the heat transfer to/from the heaterplate 60 and the engineered substrate 22. In one form, such tailoring isaccomplished by providing a gap/space “G” between the heater plate 60and the engineered substrate 22. With this gap “G,” the layered heatersystem 20 is thermally isolated from the engineered substrate 22. Inanother form, the heater plate 60 is in direct contact with theengineering substrate 22 as shown.

Referring to FIG. 6c , another form of the layered heater system 20 withthe heater plate 60 is illustrated, wherein the resistive element layer32 and terminal pads 36 are facing the support structure 22. In thisform, an intra-structure termination is provided through an aperture 62formed through the support structure 22, which allow for the passage oflead wires 64 and the housing of various components (such as theelectrical interconnects as set forth below, and/or a power controller,by way of example) inside a cavity 66 of the support structure 22. As aresult, a more compact design is provided since the termination, wiring,and components are packaged within the support structure 22.

Referring now to FIG. 7, another form of the layered heater system 20includes a core 28 defining a frame structure having a plurality ofsupport ribs 70. The position, shape (i.e. cross-sectional bendingsection), height, length, and thickness of the individual support ribs70 can thus been engineered or tailored similar to the honeycomb cells42 as set forth above, in order to provide specific heat transferrequirements and/or stiffness, depending on the requirements of the endapplication.

Referring now to FIGS. 8-10, an electrical interconnect for use inconnecting terminal pads 36 of the layered heater system 20 to a powersupply (not shown) is illustrated and generally indicated by referencenumeral 100. As shown, the electrical interconnect 100 comprises ahousing 102, which defines an extension 104. A dielectric enclosure 106is disposed within the housing 102 and is electrically sealed thereto(which is described in greater detail below). The dielectric enclosure106 defines an inner cavity 108 having a central portion 110 and alateral portion 112. The lateral portion 112 is disposed proximate theextension 104 of the housing 102. An insert 114 is disposed within theinner cavity 108 proximate the lateral portion 112 as shown. In oneform, as shown in FIG. 10, the insert 114 extends partially into thelateral portion 112. A contact member 116 is adapted for electricalcontact with the insert 114, which in one form is a coiled wire (orspring) as shown in FIG. 10. In alternate forms, the contact member 116may be a wave spring, a disk spring, a coil spring or a metal bellows.Furthermore, it should be understood that the contact member 116 can beused to force the insert 114 against the terminal pad 36 or it can beused between the insert 114 and the terminal pad 36. The contact member116 is then adapted for electrical contact with at least one terminalpad 36 of the layered heater system 20. A lead wire having a conductor122 then extends through the lead extension 104 and abuts the dielectricenclosure 106, preferably at a spot-face 124 as shown in FIG. 10. Theconductor 122 is then adapted for electrical contact with the insert 114and/or the contact member 116 to provide electrical continuity from thepower supply to the terminal pad 36.

Because one application of the electrical interconnect 100 is in avacuum environment at relatively high voltages, and also in vacuumenvironments in which plasma is introduced, the electrical interconnect100 should be electrically sealed, i.e. not allow any discharge ofelectricity to the outside environment, along with being vacuum sealed.As used herein the term “electrically sealed” should be construed tomean a close conformal fit that prevents arcing, flow or discharge ofelectricity during operation in a vacuum with relatively high voltagesapplied, for example, 1000 VAC, while allowing air to escape throughpores, or small openings or gaps so as not to create a “virtual leak”that would cause difficulty in creating and maintaining a vacuum.Various locations within the electrical interconnect should also bevacuum sealed, in addition to being electrically sealed, which areillustrated and described herein. Accordingly, in one form, the insert114 is brazed to the dielectric enclosure 106 at location A.Furthermore, the lead wire 120 is brazed to the lead extension 104 atlocation B. Additional brazing may be provided in a variety of locationsin order to properly seal the electrical interconnect 100 from anaccidental discharge of electricity.

As further shown in FIG. 8, the electrical interconnect 100 alsocomprises a cover 130 that is used to secure the electrical interconnect100 to the layered heater system 20 (preferably with mechanicalfasteners, which are not shown for purposes of clarity). Additionally, astrain relief 140 may be provided as shown, which includes in one form alower support 142 and an upper support 144, both defining grooves 146 inwhich the lead wires 120 are disposed.

Referring now to FIG. 11, another form of an electrical interconnect isillustrated and generally indicated by reference numeral 150. Thiselectrical interconnect includes a housing 152 and a dielectricenclosure 154, along with other common elements set forth above (whichare not illustrated for purposes of clarity). An alternate form of aninsert 156 is disposed within an inner cavity 158 of the dielectricenclosure 154, which is similarly brazed to the dielectric enclosure 154to provide a leak-tight interface. The insert 156 includes an internalbore 160, in which the contact member is a conductive slug 162 as shown.Further, a wave spring 164 is provided within the internal bore 158,which forces the conductive slug 160 into a firm electrical contact withthe terminal pad 36. It should be understood that the relative positionsof the conductive slug 162 and the wave spring 164 may be altered, andit should further be understood that the spring contact member 116 ofthe previous embodiment may be employed with this electricalinterconnect 150, and the conductive slug contact member 162 and wavespring 164 of this embodiment may be employed with the previousembodiment while remaining within the scope of the present disclosure.Such variations and interchangeable components should be construed asbeing within the teachings of the present disclosure.

FIGS. 12-14 illustrate another form of an electrical interconnect 200,in which the brazing of internal components is moved a distance awayfrom the electrical connection at a terminal pad 36 and also provides aheat sink to keep heat away from the electrical connection area. Asshown, the electrical interconnect includes a housing 202 with anextension 203. (It should be understood that all of the lead extensionsas set forth herein need not be integral and thus can be a separatecomponent while remaining within the scope of the present disclosure). Adielectric enclosure 204 is also provided that defines an inner cavity206 having a central portion 208 extending between opposed end portions210 and 212. The end portion 210 is disposed proximate the leadextension 203, and a plug 214, or heat sink, is disposed within the endportion 210. An insert 216, similar to those previously illustrated anddescribed extends into the plug 214 and through the central portion 208of the inner cavity 206 of the dielectric enclosure 204. A contactmember (not shown—and taking the form of any of the contact members aspreviously set forth) is then disposed within the end portion 212 and isin electrical contact with the insert 216 and the terminal pad 36 (notshown).

As further shown, the dielectric enclosure 204 includes a passageway220, which accommodates the conductor 122 as previously set forth.Additionally, the other components as set forth above, such as the cover130 and the strain relief 140, by way of example, may also be employedwith this embodiment while remaining within the scope of the presentdisclosure.

Referring now to FIG. 15, another form of an electrical interconnect isillustrated and generally indicated by reference numeral 250. Theelectrical interconnect 250 is configured to connect the lead wire 120and conductor 122 on one side of the substrate 22, while the layeredheater system 20 is disposed on the other side of the substrate 22. Theuse of a dielectric cover 123 is provided in order to provide a highvoltage electrical interconnect.

Another form of an electrical interconnect is illustrated in FIGS. 16-18and is generally indicated by reference numeral 300. As shown, theelectrical interconnect 300 comprises a dielectric enclosure 302 havingan upper cap 304 and a lower base 306. A conductive slug 308 is disposedwithin the lower base 306 as shown and in one form is bonded to theterminal pad 36. The conductive slug 308 is surrounded by an inner rim310, which is in electrical contact with conductor 312 of the lead wireassembly 314. In one form, the conductor 312 is brazed or welded to theinner rim 310 as shown. This location is both an electrical seal and avacuum seal, as designated by the “E/V” symbol. The locations thatinclude brazing or welding for an electrical seal are designated withthe “E” symbol, and the locations that include brazing or welding for avacuum seal are designated with a “V” symbol. It should be understoodthat a variety of interfaces can be provided that should be sealedelectrically, vacuum, or both in order to provide for proper operationof the electrical interconnect.

As an alternative to brazing or welding, an electrical matte (e.g., asilver braid) may be disposed between the various elements that requireelectrical sealing, such as the interface between the conductive slug308 and the inner rim 310. It should be understood that this alternateform of sealing is merely exemplary, and that other approaches tosealing (both electrically and vacuum) the various interfaces of theelectrical interconnects disclosed herein are to be construed as fallingwithin the scope of the present disclosure.

As further shown, a fastening member 320 is shown through the upper cap304, which in one form is threaded to the conductive slug 308 to securethe upper cap 304 in place, to secure the conductive slug 308 morefirmly against the terminal pad 36, and to provide for additionalelectrical sealing of the overall electrical interconnect assembly 300.The fastening member 320 is nonconductive, and in one form is a ceramicmaterial. It should be understood that although a threaded member isillustrated, other types of fastening members and materials (forexample, quick disconnects, magnetic, adhesives, among others) may beemployed while remaining within the scope of the present disclosure.

The electrical interconnect 300 also includes provisions for strainrelief of the lead wire assembly 314. First, the lead wire assembly 314is secured to the substrate 22 using blocks 330 and 332, which arefastened to the substrate 22 as shown. The blocks 330 and 332 includecutouts 334 (FIG. 17) for the lead wire assembly 314, which are sizedslightly smaller than the outer diameter of the lead wire assembly 314in order to provide an adequate amount force to reduce lateral movementof the lead wire assembly 314. Additionally, a strain relief element340, in the form of a metal tube in this particular embodiment of thepresent disclosure, is disposed within a recess 342 of the lower base306 and surrounds the lead wire assembly 314 as shown. In thisconfiguration, if the lead wire assembly 314 is deflected or moved,loads will be introduced and dissipated through the strain reliefelement 340 and into the lower base 306.

Additional forms for the electrical interconnects are illustrated anddescribed in copending application Ser. No. 11/591,203 titled “HighVoltage Heater Termination,” which is commonly assigned with the presentapplication and the contents of which are incorporated herein byreference in their entirety.

The description of the invention is merely exemplary in nature and,thus, variations that do not depart from the substance of the disclosureare intended to be within the scope of the invention. Such variationsare not to be regarded as a departure from the spirit and scope of theinvention.

What is claimed is:
 1. A layered heater system comprising: an engineeredsubstrate comprising a plurality of walls which extend in a thicknessdirection of the engineered substrate and which have a thicknessengineered for specific heat transfer requirement; a heater platedisposed on the engineered substrate; a resistive element layer formedproximate the heater plate; a protective layer formed on the resistiveelement layer; and terminal pads formed over at least a portion of theresistive element layer, wherein the terminal pads are exposed throughthe protective layer.
 2. The layered heater system according to claim 1,wherein the engineered substrate comprises an upper face sheet, a lowerface sheet, and a core disposed between the upper face sheet and thelower face sheet, and the heater plate is disposed proximate at leastone of the upper face sheet and the lower face sheet.
 3. The layeredheater system according to claim 2, wherein the core defines a honeycombstructure.
 4. The layered heater system according to claim 3, whereinthe honeycomb structure comprises a plurality of cells defined by theplurality of walls.
 5. The layered heater system according to claim 3,wherein the honeycomb structure comprises a plurality of cells having aperipheral size, and the peripheral size is tailored for specific loadcarrying capability.
 6. The layered heater system according to claim 1,wherein the plurality of walls are a plurality of support ribs forsupporting the heater plate thereon.
 7. The layered heater systemaccording to claim 1, further comprising a dielectric layer formed onthe heater plate, wherein the resistive element layer is formed on thedielectric layer.
 8. The layered heater system according to claim 7,wherein the dielectric layer is directly formed on the heater plate by alayered process selected from a group consisting of thick film, thinfilm, thermal spray, and sol-gel, and the resistive element layer isdirectly formed on the dielectric layer by the layered process.
 9. Thelayered heater system according to claim 1, further comprising at leastone temperature sensor.
 10. The layered heater system according to claim9, further comprising a thermowell disposed between the heater plate andthe engineered substrate to receive the at least one temperature sensor.11. The layered heater system according to claim 1, further comprising agap between the heater plate and the engineered substrate.
 12. Thelayered heater system according to claim 1, wherein the heater plate isin direct contact with the engineered substrate.
 13. The layered heatersystem according to claim 1, wherein the resistive element layer and theterminal pads face the engineered substrate, and the engineeredsubstrate defines at least one aperture and an internal cavity forhousing lead wires from the terminal pads and components of the layeredheater system.
 14. The layered heater system according to claim 1,further comprising: an electrical interconnect for use in a connectingthe terminal pads to a power supply comprising: a dielectric enclosuredefining an inner cavity having a central portion; and a contact memberdisposed within the central portion of the inner cavity of thedielectric enclosure, the contact member being adapted for electricalcontact with the terminal pad.
 15. The layered heater system accordingto claim 14, wherein the electrical interconnect is in a high voltagevacuum environment.
 16. A layered heater system comprising: anengineered substrate comprising an upper face sheet, a lower face sheet,and a core disposed between the upper face sheet and the lower facesheet; a dielectric layer formed proximate at least one of the upperface sheet and the lower face sheet; a resistive element layer formed onthe dielectric layer; a protective layer formed on the resistive elementlayer; and terminal pads formed over at least a portion of the resistiveelement layer, wherein the terminal pads are exposed through theprotective layer.
 17. The layered heater system according to claim 16,further comprising a heater plate disposed proximate at least one of theupper face sheet and the lower face sheet, wherein the dielectric layeris disposed on the heater plate.
 18. The layered heater system accordingto claim 16, further comprising: an electrical interconnect forconnecting the terminal pads to a power supply, the electricalinterconnect comprising: a dielectric enclosure defining an inner cavityhaving a central portion; and a contact member disposed within thecentral portion of the inner cavity of the dielectric enclosure, thecontact member being adapted for electrical contact with the terminalpad.
 19. The layered heater system according to claim 16, wherein theelectrical interconnect is in a high voltage vacuum environment.
 20. Thelayered heater system according to claim 16, wherein the engineeredsubstrate is configured to control heat transfer from the resistiveelement layer disposed proximate the at least one of the upper facesheet and the lower face sheet to the other one of the upper face sheetand the lower face sheet.